RPN calculator
Start date: 20170227
Submission due: 20170301 9:00am
Requirements:
1. Basic function: +, -, *, /, ^ are required. Please upload your code and run result screenshots.
2. further function: sin(), cos(), log(), etc. are encouraged. You will get bonus
3. further extension: RPN expression convertor --- postfix --> infix . You will get more bonus



References:
def postfix_evaluation(s):
    s=s.split()
    n=len(s)
    stack =[]
    for i in range(n):
        if s[i].isdigit():
          #append function is equivalent to push
            stack.append(int(s[i]))
        elif s[i]=="+":
            a=stack.pop()
            b=stack.pop()
            stack.append(int(a)+int(b))
        elif s[i]=="*":
    **********
        elif s[i]=="/":
    **********
        elif s[i]=="-":
               **********
    return stack.pop()
 
#space separtor is required , for solving 2 or more digits .
s="10 2 8 * + 3 -"
val=postfix_evaluation(s)
print(val)
 
Openbook references of stack:
http://openbookproject.net/thinkcs/python/english3e/stacks.html